When you sleep, you sweat out and breathe out some water, but how much is normal to lose, assuming you're not actively trying to make yourself sweat?

  • In my personal experience it has ranged from 0.5kg - 1kg. This is a sample size of 1 but it may give some indication.
    – Kenshin
    Oct 9, 2017 at 4:52

1 Answer 1


This is much easier to measure than to calculate.

After urinating and before going to bed, weigh yourself. After getting up, urinating and having a bowel movement (bm is mostly water) weigh yourself in the same clothes. The difference in weight is mainly due to water loss (urine loss, sweating and insensible perspiration); this will be likely ~0.5 kg or more, mostly depending on how much you sweat.

The amount of water lost by breathing is about the same as the amount of metabolic water produced in your body in the same time (NAP.edu).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.